Hip and Knee Actuation Systems for Lower Limb Orthotic Devices

Abstract

A lower limb orthotic device includes a thigh link connected to a hip link through a hip joint, a hip torque generator including a hip actuator and a first mechanical transmission mechanism interposed between the thigh link and the hip link, a shank link connected to the thigh link through a knee joint, a knee torque generator including a knee actuator and a second mechanical transmission mechanism interposed between the thigh link and the shank link, and a controller, such as for a common motor and pump connected to the hip and knee torque generators, for regulating relative positions of the various components in order to power a user through a natural walking motion, with the first and second mechanical transmission mechanisms aiding in evening out torque over the ranges of motion, while also increasing the range of motion where the torque generators can produce a non-zero torque.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61 / 099,817 entitled “Hip and Knee Actuation for Orthotic Devices”, filed Sep. 24, 2008.BACKGROUND OF THE INVENTION[0002]The present invention relates to the field of powered orthotics.[0003]In general, devices for aiding crippled persons in walking are known in the art, as demonstrated by U.S. Pat. No. 4,557,257 to Fernandez. However, such devices are bulky and burdensome to manipulate. Other systems, such as the Lower Extremity Exoskeleton set forth in U.S. Patent Application Publication No. 2006 / 0260620, establish a means for providing power at a knee joint. However, there is still seen to exist a need for an orthotic device which can be made compact and wearable by a person, but also provides the power necessary to aid a person in carrying a load. Additionally, there is seen to exist, a need for an orthotic device which powers both a thigh joint and a k...

AI Technical Summary

Benefits of technology

[0004]In general, the present invention is directed to lower limb orthotic devices and, more specifically, to hip and knee actuation systems for orthotic devices. In particular, a lower, limb orthotic device to be worn by a user includes a thigh link adapted to couple to a user's lower limb; a hip link; a hip joint rotatably coupling the thigh link and the hip link to allow flexion and extension between the thigh link and the hip link; a power source; and a hip torque generator coupled to the thigh link and the hip link. In a preferred form, the hip torque generator includes a linear hydraulic hip actuator including a piston; a mechanical transmission mechanism connecting the linear hydraulic hip actuator to the thigh link; an eidetic motor; and a hydraulic pump driven by the electric motor to, pressurize hydraulic fluid within a hydraulic circuit to extend or retract the linear hydraulic hip actuator. Preferably, the orthotic device also includes a knee torque generator coupled to the thigh link and a shank link. The knee torque generator preferably includes a linear hydraulic knee actuator including a piston; a mechanical transmission mechanism connecting the linear hydraulic knee actuator to the shank link; and a hydraulic valve located between the linear hydraulic knee actuator and the hydraulic circuit to regulate the flow of hydraulic fluid between the linear hydraulic knee actuator and the hydraulic circuit. The hydraulic valve can be in the form of a three or four-port valve.

[0005]The hydraulic circuit can take on a variety of forms. In one preferred embodiment, the hydraulic circuit includes first and second pilot check valves which regulate the flow of hydraulic fluid between first and second fluid ports of a non-symmetrical linear hip actuator, a non-symmetrical linear knee actuator and a fluid, reservoir, while a three-port valve regulates fluid flow between the non-symmetrical linear knee actuator and the hydraulic circuit with this configuration, the hydraulic circuit provides different effective gear ratios such that the hydraulic pump turns at a first rate order to extend the piston of the hydraulic hip actuator and at a second rate in order to retract the piston at the same speed, and wherein the gear ratio allows for fast motion at low torque during a swing phase of the orthotic device and a slower motion at high torque during a stance phase of the orthotic device. In any case, the overall lower limb orthotic device employs a common motor driven pump arrangement for both hip and knee torque generators to power a user through a natural walking, motion, with the first and second mechanical transmission mechanisms aiding in evening out torque over the ranges of motion for the joints of the device, while also increasing the range of motion where the torque generators can produce a non-zero torque. Additional objects, features and advantages will become more readily apparent from the following detailed description made with reference to the drawings wherein like reference numerals refer to corresponding parts in the several views.

Problems solved by technology

However, such devices are bulky and burdensome to manipulate.

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